U.S. Sen. Scott Brown and Elizabeth Warren strung together campaign stops from morning to night on Sunday, as the campaign clock clicked down to Election Day, with each candidate launching partisan volleys and trying to create a sense that their campaign was ready to claim victory Tuesday night.

Mr. Brown, the Republican seeking re-election, held a large rally at Faneuil Hall, where his campaign was saluted by former Gov. William F. Weld and about 700 supporters. He then talked to a group of 150 seniors at a senior center in Quincy, where his campaign volunteers served up chowder, cake and cookies.

While talking about a disputed Republican claim that Medicare benefits would be cut as part of federal health care reforms, Mr. Brown disclosed publicly for the first time that his father, Claude B. Brown, a former city councilor from Wakefield who suffers from Alzheimer’s disease, does not have long to live.

He said both his parents are using their Medicare benefits, after paying into the system during their lifetimes.

“There was a contract, something my mom and dad are taking advantage of right now,” Mr. Brown said. Then he told the seniors, “My dad has about three to four weeks left to live and he is taking advantage of that contract. Medicare is helping him.”

Mr. Brown, who wants to repeal Obamacare, acknowledged that the claim that cuts are pending in Medicare benefits has been denied by some groups, including the American Association of Retired Persons. But he advised them to ignore those claims, and trust their own judgment.

“On this Medicare issue, you have seen back and forth. AARP says one thing. I say another. My opponent says another. Do this — call your doctor. Call your hospital. Call your nursing home and ask them,” he said. “They will tell you that it will dramatically affect the care and coverage you will get.”

A few miles away in Braintree, there was standing room only as about 500 people packed the high school auditorium for Ms. Warren, the Democrat seeking to oust Mr. Brown. She showed up with U.S. Sen. John Kerry for a get-out-the-vote rally.

Mr. Kerry, who played Mitt Romney as a debating partner while President Barack Obama practiced for his debates, cracked a few jokes about spending so much time acting as the Republican nominee. He then disputed Mr. Brown’s claim about pending Medicare cuts.

“It’s not true,” he said.

“They are lying about what happens with Medicare. They’ve got robo-calls going into seniors’ homes saying Barack Obama cut $716 billion from Medicare. No, folks. Barack Obama put money into the health care system to provide people with mammograms, wellness visits, with prescription drugs,” Mr. Kerry said. “He didn’t cut it. He made it stronger and extended its life for 10 additional years.”

Ms. Warren got one standing ovation after another as she ran through her stump speech, and she said she would not support any cuts in Medicare, Social Security or health care benefits if she is elected.

She also criticized Mr. Brown for taking “the right-wing Grover Norquist pledge” not to raise taxes, even from billionaires, millionaires or big oil companies, and for blocking extension of tax cuts for the middle class unless top earners also had those tax cuts extended.

“He took a vote last month to say 98 percent of the families across the commonwealth and across the country, and 97 percent of the small businesses would be held hostage, that your taxes will go up Jan. 1, unless there are bigger tax breaks for the top 2 percent,” Ms. Warren said.

“It’s all on the line here,” she said summing up the campaign. “It’s about whether we are going to have a Senate that will work with our president, or a Senate that will block him at every possible chance.”

She continued, “It’s not just about us. It’s about our children. It’s about our grandchildren. This truly is about the kind of people we are, the kind of country we are going to build, about whose side America stands on.”

A poll released Sunday by a Western New England University Polling Institute survey of 535 likely voters found 50 percent favored Warren, 46 percent backed Brown and 4 percent were undecided. The poll has a margin of error of plus or minus 4 percentage points.

The appearance of Weld and Kerry on the campaign trail brought to mind an earlier contest. The two battled in another high-profile Senate race in 1996 when Weld challenged Kerry for his Senate seat and lost.

Both national parties are keeping a close eye on the Massachusetts election as they battle for control of the Senate.

The race is the costliest in state history. As of mid-October, Brown and Warren had spent a combined $68 million on the race.

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